The present invention relates to a substrate having a plurality of components mounted on one surface thereof and particularly to a method for mounting contact surfaces on contact strips which interconnect the components.
In the electronics industry, much use is being made at the present time of substrates on which components connected by strips conductors are mounted. These components are often mounted on the substrates by a relatively new technique known as surface mounting. This technique uses sophisticated pick-up and positioning machines by which the components are mounted on the substrates made of plastics or ceramic boards. In order to hold these components in place for further processing, a solder paste mixed with adhesive is used. Alternatively, the adhesive and the solder paste may be applied separately in the form of two separate substances. To achieve secure fastening, infrared radiation is then applied in such a manner that the resulting induced heat melts the solder particles in the adhesive, thus bringing about an electrical connection between component and substrate.
If often happens in practice that these substrates carrying components connected by strips conductors must be able to function as interchangeable units. The substrates therefore have plug-in edges which are provided with contact surfaces. Preferably, these contact surfaces should be gripped by an edge connector with the smallest possible spring or clamp force. Otherwise, rapid wear may occur or excessive force will be required to make the plug-in connection. In practice, attempts have been made to prevent this by using gold plated contact surfaces. Since this is not practical using current techniques, the contact surfaces are activated by, for example, being tin plated.